The present invention generally relates to a cooking appliance such as an electric-oven, an electronic range, compound ovens, etc. Operation keys in an operating portion of such cooking appliances may be concentrated for improving the use thereof, and cooking performance in an automatic cooking operation may be improved.
The electronic control art has conspicuously penetrated into recent home appliances with the appearance of microcomputers. Cooking appliances are provided with various functions and are especially realized with combined temperature sensors, humidity sensors and microcomputers. One of the functions is an automatic cooking operation.
A cooking appliance for directly detecting the surface temperature of a cooked item with the use of an infrared ray temperature sensor so as to control a heating means, a cooking appliance for inserting a temperature probe into the cooked item so as to directly detect the temperature for controlling the heating means, a cooking appliance for detecting with a thermistor the atmospheric temperature within the cooking chamber so as to effect an automatic cooking operation in accordance with the information relating to the circumstances of the temperature within the cooking chamber, and other cooking appliances have been invented for practical use. In a grill cooking operation or an oven cooking operation with a cooking appliance using an infrared ray temperature sensor, the heat-proof sensor itself becomes a problem as the temperature of the oven interior rises up to 250.degree. C. through 300.degree. C. Actually, the sensor is thermally evacuated, with the temperature of the cooked item being measured to approximately 60.degree. C. Thereafter, the temperature is adapted to be estimated with a temperature grade reaching to 60.degree. C. Therefore, considerable dispersion is caused in the finishing of the cooking operation. In a cooking appliance for detecting the temperature, with a temperature probe being inserted directly into the cooked item, it is positive in terms of the temperature detection, but with problems in that convenience is restricted, and that sanitation is inferior. An automatic cooking method of a cooking appliance using a conventional thermistor, the method most often adopted, will be described hereinafter. FIG. 13(b) shows change characteristics in the atmospheric temperature within the cooking chamber from the cooking start. The temperatures are detected with the thermistor. The cooking time of the cooked item is determined with a numerical equation 1. Namely, an elapsed time t1, taken for the atmospheric temperature to reach a certain temperature T, is measured, and a time t, provided through the multiplication of the time t1 by a constant K peculiar to the food, is made a cooking time. EQU t=t1+K.times.t1 (numerical equation 1).
When, after finishing a cooking operation with the working appliance, cooking has been performed in succession prior to cooling of the cooking appliance, the temperature within the cooking chamber becomes extremely high. FIG. 13(b) shows the change characteristics in the atmospheric temperature within the cooking chamber from the start of cooking in this case. The atmospheric temperature is once lowered or is raised. FIG. 13(b) is different from FIG. 13(a). This is because the heat within the cooking chamber is absorbed into the cooked item for some time if the cooking operation starts when the initial temperature within the cooking chamber is high. In this case, the cooking time cannot be decided with the numerical equation 1. Conventionally the cooking time is decided roughly. A cooking appliance which is superior in cooking performance and operation is hard to realize with this method.
It is said that there is considerable interrelation, depending upon the cooking category, among the finish of cooking, the surface temperature of the cooked item, and so on. An ideal cooking appliance can be realized, even in terms of the finishing of cooking of the cooked item, and also in the concentration of operating keys in cooking categories, if the surface temperature during the cooking operation of the cooked item can be positively recognized with real time without contact. The cooking degree can be recognized by the detection of the surface temperature of the cooked item, and so on. As such a problem as described hereinabove exists, it is difficult to realize such a cooking appliance.
Recently researches into applying a neural network into various fields have been actively engaged. Special cells called neurons exist in a living body. The neurons are combined in large amounts as operation elements in the brains of a living creature. Through neurons a brain has flexible information processing referred to as "learning", "storing", "judging", "association" and so on A model called a neural network is proposed for numerically analyzing the characteristics of signal transmission of the nerve cells. The possibility of various applications are checked.